Proteins Flashcards
What are proteins made up of?
Amino acids
What are amino acids made up of?
- Central carbon bonded to hydrogen
- Amino group (NH2)
- Carboxylic group (COOH)
- R group (side chain)
R group
Determines the physical and chemical structure of a protein
How are amino acids joined to form proteins?
Through a peptide bond which requires energy and removes a molecule of water
How many amino acids are there?
140
How many amino acids make up a protein?
20
Side chains
- Large or small
- Charged or neutral
- Form hydrogen or disulfied bonds with other amino acids
- Hydrophobic or hydrophilic
Primary protein structure
- Amino acid sequence
- R groups located on opposite sides of chains
- No interactions
Secondary protein structure
- Determined by number and sequence of amino acids
- Formed by chemical reactions in the primary structure
- Space between amino acids
Tertiary protein structure
- 3D structure
- Formed by interactions of amino acids or side chains
- Globular-like structure
- Fibrous structure
Quaternary protein structure
- Space between sub-units
- Formed by 2 or more polypeptide chains interacting
- Insulin and haemoglobin
Digestion definition
Macromolecules in food are broken down into their component small-molecule subunits
How are proteins digested in the stomach?
Low pH
What is pepsin?
Proteolytic enzyme which cleaves proteins into smaller peptides at pH 2
After the stomach, where is protein digested?
Small intestine where it is exposed to proteolytic enzymes
How does the pancreas help to digest protein?
Produces proteolytic enzymes which produces a mixture of amino acids and oligopeptides
How is the protein further broken down?
By membrane bound enzymes where it is absorbed as amino acids, di and tripeptides
Where do amino acids go in the body?
Epithelial cells then into capillaries and plasma where it can be oxidised to provide energy
Why are amino acids required?
Protein synthesis
Name the 4 functions of protein synthesis
Structure, protection, enzymatic, transport/communication
What is deamination?
Removal of the amino group
What are the products of deamination?
Ammonia and oxoacid
What is another process for amino acids?
Transamination
What is transamination?
When an amino acids becomes a different amino acid via de-novo synthesis
How is protein needed estimated?
The amount of nitrogen needed to reach nitrogen equilibrium in adults
What is the nitrogen requirement for children?
Positive balance
How do you calculate protein requirements?
Nitrogen balance x 6.25
